1. Field of the Invention
This invention relates to the use of short-chain, terminally blocked alkyl polyethylene glycol ethers as foam inhibiting additives in low-foam cleaning compositions.
2. Statement of Related Art
Aqueous cleaning compositions intended for institutional and industrial use, particularly for the cleaning of metal, glass, ceramic and plastic surfaces, generally contain substances which are capable of counteracting unwanted foaming. In most cases, foam inhibiting additives are used because the soil particles become detached from the surfaces being cleaned and enter the cleaning baths where they act as foam generators. In addition, the use of anti-foam agents may also be necessitated by the fact that the cleaning compositions themselves contain constituents which give rise to unwanted foaming under the prevailing working conditions, for example anionic surfactants or nonionic surfactants which foam at the working temperature.
U.S. Pat. No. 4,548,729 describes the use of polyethylene glycol ethers corresponding to the following formula as foam inhibiting additives in cleaning compositions: EQU R.sup.1 -O-(CH.sub.2 CH.sub.2 O).sub.n -R.sup.2
wherein:
R.sup.1 is a linear or branched C.sub.8 -C.sub.18 alkyl or alkenyl radical, PA1 R.sup.2 is a C.sub.4 -C.sub.8 alkyl radical, and PA1 n is a number of 7 to 12. PA1 R.sup.1 is a linear or branched C.sub.6 -C.sub.18 alkyl or alkenyl radical, PA1 R.sup.2 is a C.sub.4 -C.sub.8 alkyl radical, and PA1 n is an integer of from 2 to 6.
One of the limitations associated with the use of these foam inhibitors is that they do not provide acceptable foam inhibition properties at lower temperatures, i.e., below 20.degree. to 25.degree. C., where it is desirable to maintain such properties.